Isurus

Although fossil teeth of Isurus have been reported from as early as the Late Cretaceous,J. B. Reeside. 1955. Revised interpretation of the Cretaceous section on Vermilion Creek, Moffat County, Colorado. Wyoming Geological Association Guidebook - 1955 85–88R. Zangerl and R. E. Sloan. 1960. A new specimen of Desmatochelys lowi Williston: a primitive cheloniid sea turtle from the Cretaceous of South Dakota. Fieldiana: Geology 14(2):7-40 they are likely to be of a shark with a similar dentition, Cretoxyrhina; since at one point they were considered to be the same (now defunct) genus Oxyrhina,{{Cite book |last=Agassiz |first=Louis |url=http://dx.doi.org/10.5962/bhl.title.4275 |title=Recherches sur les poissons fossiles ... |date=1833 |publisher=Petitpierre |location=Neuchatel|doi=10.5962/bhl.title.4275 }} and modern referrals to Isurus in the Cretaceous are scant. The earliest appearance of Isurus proper seems to be during the Oligocene with Isurus desori.Andre Pharisat & Norbert Micklich (1998) Oligocene fishes in the western Paratethys of the Rhine Valley Rift System, Italian Journal of Zoology, 65:S1, 163–168, {{doi|10.1080/11250009809386808}}Merle, D. & Baut, J.-P. & Ginsburg, L. & Sagne, C. & Hervet, S. & Carriol, R.-P. & Venec-Peyre, T. & Blanc-Valleron, M. & Mourer-Chauviret, C. & Arambol, D. & Viette, P. (2002). Découverte d'une faune de vertébrés dans l'Oligocène inférieur de Vayres-sur-Essonne (bassin de Paris, France) : biodiversité et paléoenvironnement. Comptes Rendus Palevol, 1(2), 111–116. {{doi|10.1016/S1631-0683(02)00018-0}}

There has been much debate and speculation about the evolutionary origin and relationships between Isurus and its closest relatives, including the extant great white shark (Carcharodon carcharias). Molecular clock analyses place the last common ancestor of Isurus and Carcharodon between 43–60 million years ago during the Late Paleocene-Early Eocene.Martin, A. P. (1996). "Systematics of the Lamnidae and the Origination Time of Carcharodon carcharias Inferred from the Comparative Analysis of Mitochondrial DNA Sequences". In Klimley, A. P.; Ainley, D. G. (eds.). Great White Sharks: The Biology of Carcharodon carcharias. Academic Press. pp. 49–53. {{doi|10.1016/B978-0-12-415031-7.X5000-9}}. {{ISBN|978-0-12-415031-7}} This insight should guide efforts to better resolve the fossil ancestry of both lineages, by providing a window of time in which to search for ancestor candidates.

Many fossil species of Lamnids have historically been placed under Isurus, which are now largely considered separate genera. These include species of Carcharodon (Cosmopolitodus) like C. hastalis, C. planus,Ehret, D.J., Macfadden, B.J., Jones, D.S., DeVries, T.J., Foster, D.A. and Salas-Gismondi, R. (2012), Origin of the white shark Carcharodon (Lamniformes: Lamnidae) based on recalibration of the Upper Neogene Pisco Formation of Peru. Palaeontology, 55: 1139–1153. {{doi|10.1111/j.1475-4983.2012.01201.x}} species of Macrorhizodus,White, E., 1956. The Eocene Fishes of Alabama. Bulletin of American Paleontology, 36 (no. 156): PRI. pp 122–152.Glikman, L.S., 1964. Akuly paleogena i ikh stratigraphicheskoe znachenie. Akademii Nauk Soyuza Sovetskikh Sotsialisticheskikh Respublik, 1–228 Moscow. Isurolamna,Le Hon, H., 1871. Préliminaires d'un mémoir sur les poissons tertiaries de belgique. Brussels, pp. 1–15.Leriche, M. 1905. Les poissons tertiaires de la Belgique. II. Les poissons éocènes. Mém. Mus. Roy. Hist. Natur. Belig., 11(3), p49-228. and others.

The two living species are the shortfin mako shark (I. oxyrinchus) and the longfin mako shark (I. paucus). They range in length from {{convert|2.5|to|4.5|m|ft|abbr=on}},{{Cite web |title=Shortfin Mako Shark |url=https://myfwc.com/wildlifehabitats/profiles/saltwater/sharks/shortfin-mako-shark/#:~:text=Maximum%20length%2012%20feet.,live%20up%20to%2030%20years. |access-date=2025-01-23 |website=Florida Fish And Wildlife Conservation Commission |language=en}} and have an approximate maximum weight of {{convert|680|kg|lb|abbr=on}}.{{Citation needed|date=May 2023}} They both have a distinctive blue-gray color scheme common among mackerel sharks.

The genus contains these species:{{Cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=34613 |title=Fossilworks |access-date=2021-12-17 |archive-date=2022-10-31 |archive-url=https://web.archive.org/web/20221031071657/http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34613 |url-status=live }}

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• Isurus oxyrinchus (Rafinesque, 1810) (shortfin mako shark)Smith, J.L.B. [http://hdl.handle.net/10962/d1018543 Sharks of the Genus Isurus Rafinesque, 1810]. Ichthyological Bulletin; No. 6. Department of Ichthyology, Rhodes University, Grahamstown, South Africa
• Isurus paucus (Guitart-Manday, 1966) (longfin mako shark)Tony Ayling & Geoffrey Cox, Collins Guide to the Sea Fishes of New Zealand, William Collins Publishers Ltd, Auckland, New Zealand 1982 {{ISBN|0-00-216987-8}}
• †Isurus desori (Agassiz, 1843)
• †Isurus retroflexus (Agassiz, 1843)

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• Shortfin mako shark
• Longfin mako shark
• White sharks
• List of prehistoric cartilaginous fish
• Shark meat

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{{Lamniformes}}

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Category:Extant Late Cretaceous first appearances

Category:Shark genera

Category:Taxa named by Constantine Samuel Rafinesque

Category:Taxa described in 1810